Ouyang Jian 歐陽建 (268-300 CE), courtesy name Ouyang Jianshi 歐陽堅石, was a philosopher of the Western Jin period 西晉 (265-316). He came from Bohai 渤海 (modern Nanpi 南皮, Hebei) from a rich family in the province of Jizhou 冀州, and occupied the offices of secretarial court gentleman (shangshu lang 尚書郎) and then governor (taishou 太守) of the commandery of Fengyi 馮翊. His career found an abrupt end when he was implicated into the political struggles of the ruling dynasty (see rebellion of the Eight Princes). Ouyang Jian was killed by Sima Lun 司馬倫, the Prince of Zhao 趙.
In his essay Yan jin yan lun 言盡意論, Ouyang Jian criticized the literary diffuseness of the "School of the Mystery" (xuanxue 玄學), a Daoist attitude among the intellectuals of his time. With the concept of shape (xing 形) and name (ming 名) he brought forward the argument that language is indeed sufficient to express all thoughts and concepts. This is a contradiction to the School of Mystery with its proposition that words are not sufficient to explain what the Way (dao 道), the fundament of nature, is. Ouyang Jian's explanation of the usefulness of language was supported by the assumption that concrete objects and matters are objective and have nothing to do with the mind of humans. Language is, nonetheless, a necessary instrument of expression. Without language, circumstances and objects cannot be perceived and described correctly. It is a much more useful, and indispensable, means of perception, and therefore much more important that intuition, as the adherents of the School of Mystery, believed. Ouyang Jian says that if things change, their designation has also to follow. Language is subject to objective change (yan yin li er bian 言因理而變 "language changes with the underlying patterns"), like an echo responds to its source and the shadow corresponds to its source.